Presently available copper alloys containing ten to fifty ppm each of manganese and selenium are known from U.S. Pat. No. 4,311,522. These copper alloys have a softening temperature of about 425.degree. C. In an industrial environment, during fabrication, the in line annealing process involves temperatures of 480.degree. C. to 540.degree. C. Such temperatures destroy the thermal stability of these prior art alloys and renders them useless for high temperature applications. Typical applications for high conductivity copper alloys include rotor windings for various devices such as motors, generators and solenoids, welding electrodes and, heat sink arrangements for the removal of heat from electronic devices. Currently, these prior art alloys are produced by conventional ingot metallurgy techniques. Such techniques require the material to be homogenized and hot worked at 800.degree. C. to 900.degree. C. in order to break up the cast structure. Subsequently, thermal stability is imparted to these alloys by extensive cold work.